Definition of "Defect" :

noun: a mark or flaw that spoils the appearance of something (especially on a person's body)

noun: a failing or deficiency

"That interpretation is an unfortunate defect of our lack of information."

noun: an imperfection in a bodily system

"Visual defects."

noun: an imperfection in an object or machine

"If there are any defects you should send it back to the manufacturer."

verb: desert (a cause, a country or an army), often in order to join the opposing cause, country, or army